Uptime

Uptime is the percentage of time a tool is available for production, a key metric for semiconductor fab capacity and efficiency. Calculation: Uptime = (Total time - Downtime) / Total time × 100%. E-CAM states: (1) Productive—running production wafers; (2) Standby—available but waiting for wafers; (3) Engineering—experiments, setup, not available; (4) Scheduled downtime—planned PM; (5) Unscheduled downtime—failures, repairs. Uptime vs. Availability: uptime = scheduled production time, availability (OEE component) = uptime / (uptime + downtime). Industry targets: >95% uptime for mature tools, >90% for new tools or complex processes. Uptime drivers: (1) Reliability—MTBF (mean time between failures); (2) Maintainability—MTTR (mean time to repair); (3) PM efficiency—PM duration vs. scheduled; (4) Spare parts availability; (5) Technician skill level. Uptime improvement strategies: predictive maintenance (catch failures early), PM optimization (reduce PM time and frequency), hot-swap capabilities (quick component replacement), remote diagnostics (faster troubleshooting). Uptime impact: each 1% uptime improvement on bottleneck tool can significantly increase fab output. Tracking: automated uptime monitoring via SECS/GEM tool state reporting to MES. Critical metric balanced against process quality and tool lifetime considerations.